Networkers get a traction transplant

Working in partnership with HSBC Rail and Brush Traction, Hitachi is replacing key drive components to improve the performance of 97 Networker EMUs used on routes in southeast London and Kent

Hirofumi OjimaManager, Rail SystemsHitachi Europe Ltd

FULL-SCALE combined testing with a prototype set of EMU traction equipment is now getting underway at Hitachi's Mito facility in Japan. The fully-tested package is due to be delivered to the customer in the first quarter of 2008.

Hitachi has been contracted by rolling stock leasing company HSBC Rail to replace the traction equipment on two batches of Networker EMUs used on suburban services in southeast London, under a deal which also includes maintenance of the replacement package, initially for 10 years. The programme aims to virtually eradicate traction equipment failures within the fleet; the Hitachi traction package is targeted to deliver 600 000 miles in mean distance between service-affecting failure, which would be comfortably ahead of the level achieved by other mid-life trains in the UK market.

Each Networker's traction equipment will be exchanged in three days using a 'pit-stop' approach to minimise fleet down-time. The replacement traction package has a design life of 25 years.

The intention of the refit is to improve the performance and reliability of the four-car units, which have now been in service for almost 15 years. Hitachi is responsible for integrating the replacement package into the train, removing redundant equipment, commissioning the modified units, and re-introducing the fleet into revenue service.

Greater flexibility

The Networker EMUs operate on the 750 V DC third rail network in southeast England. Built in the early 1990s, the fleet consists of five sub-classes. Class 465/0 and 465/1 four-car sets were built by BREL (now part of Bombardier) with Brush traction equipment. The Class 465/2 and 465/9 four-car and Class 466 two-car units were supplied by GEC Metro-Cammell, now Alstom (Table 1).

Originally ordered by British Rail, the fleet was split between two rolling stock leasing companies at privatisation. The 97 BREL-built units are currently owned by HSBC Rail, and operated by Govia subsidiary London & South Eastern Railways, trading as Southeastern.

Each four-car unit has two DMOS driving motor cars and two intermediate trailer vehicles. All four axles on each DMOS are powered, with a single traction package feeding the four motors. Thus there are 194 traction packages in total.

The main impetus for updating the traction package was the need to improve the reliability of the Class 465/0 and 465/1 units. HSBC Rail and Southeastern conducted a reliability and availability study of all of the vehicle systems, and concluded that, in addition to other modifications, the best way to improve reliability would be to replace the traction equipment.

Suppliers were approached to provide a replacement traction system which would fit seamlessly into the existing vehicles and significantly improve reliability and performance. Hitachi offered its latest traction technology, coupled with design considerations aimed at enhancing the operational flexibility of the modified units.

Proven track record

At the same time, Hitachi won the contract to supply Class 395 trainsets for domestic services on the Channel Tunnel Rail Link, also to be operated by Southeastern. Hitachi had therefore gained a thorough understanding of the third rail DC network through extensive preparatory work in bidding for UK contracts.

With the assistance of HSBC Rail, Hitachi's first introduction to the UK rail industry came with the development of the dual-voltage Verification Train, which ran for two years in 2002-03. Originally aimed at a proposal for 180 inner-suburban EMU cars to operate alongside the Networkers, the V-Train project was intended to demonstrate the compatibility of Hitachi's traction technology with both AC and DC routes in the UK, including the CTRL.

These trials marked a significant step forward for Hitachi Rail Systems. The V-Train proved the compatibility of the standard Hitachi A-Train electrical system with the UK's rail infrastructure, which is a significant hurdle in the acceptance and delivery of new trains. The V-Train also validated the performance of the Hitachi equipment under specific UK track and climatic conditions, and minimised the EMC safety case acceptance risk. It was highly significant in helping Hitachi to win the Class 395 and Class 465 contracts.

Technology advances

The Networker units were the first EMUs ordered by British Rail with three-phase traction drives, but propulsion technology has improved considerably since they were constructed. For example, the replacement traction drive will use IGBT technology rather than GTO thyristors. Advances in microprocessor control will be utilised together with a self-ventilating design which does not require forced air cooling. All these changes will contribute to improved reliability and availability.

The design process centred on three main elements:

removal of perceived 'risk to reliability' components;

feedback from studies of existing failure modes;

ensuring a high level of performance despite the failure of some components.

For example, the reliability risks were reduced by removing the inverter and brake resistor cooling fans which are generally acknowledged as vulnerable. To maintain train performance following a component failure, the replacement traction system was designed in such a way that a four-car unit can still meet the advertised timetable with one of its four inverters cut out.

Modification

The principal components to be replaced are the propulsion drive and brake resistors. The inverter and brake resistor blower units and their respective motors will be removed, as the replacement brake resistors will be cooled by natural convection. Side skirts around the traction modules will be removed to improve the airflow. The traction motors, gearboxes and auxiliary power supplies will be re-used.

This project is the first time in the UK that modern three-phase power converters have been integrated into an older EMU design, and this has thrown up some novel difficulties. The Hitachi equipment meets modern design standards, whereas the existing traction equipment and the unmodified equipment remaining on the vehicle comply with the standards that applied when they were built. Detailed interface studies had to be undertaken to identify all potential conflicts, and this information was fed into the interface design for the new traction equipment.

To further mitigate this risk, Brush Traction, as manufacturer of the original traction system, has been employed as interface and installation design consultant. Additional mitigation measures including specific electrical interface testing on the current vehicles and removal of equipment from some existing vehicles to investigate mechanical aspects of the conversion.

Another survey was needed to determine any significant differences between the original Class 465/0 units and the later Class 465/1 variants. In fact, this concluded that there were no discernable differences between the two types which would influence the fitting of the replacement traction equipment.

Nevertheless, the contract provides for an extensive period of time for the prototype installation, and for static and dynamic on-track testing to confirm the interface design.

Three-year timescale

Following the completion of the prototype replacement package at the end of 2007, the equipment is due to spend several months undergoing testing at Hitachi's traction production and test site in Mito. As well as type testing, there will be a series of combined tests using four of the existing Networker traction motors which have been sent to Japan.

After the bench testing, the prototype traction package will be shipped to the UK in the first quarter of 2008. The equipment will then be installed on one unit for dynamic testing and commissioning, although it has not yet been decided whether this will be a Class 465/0 or 465/1.

Brush Traction has been subcontracted to undertake installation design and fit the prototype equipment. This builds on a growing working relationship between the two companies, which also includes the 'Hayabusa' hybrid test train (RG 7.07 p428), where Brush was responsible for integrating the Hitachi-built battery-assisted traction drive into an existing High Speed Train power car.

Following modification, the prototype Networker will be based at Hitachi's new Ashford depot for testing on the Southeastern network. It is anticipated that the first unit will commence testing towards the end of 2008.

Following the completion of testing with the prototype, the full-scale production modification of the fleet is due to take place during 2009 and 2010. This work will be done at Ashford, alongside the completion of commissioning for the Class 395 fleet.

CAPTION: HSBC Rail expects the reliability of its 97-strong Networker fleet to rival that of a new-build train once Hitachi traction equipment has been installed Photo: Southeastern